'''
a=1,b=2,不用中间变量交换a和b的值？
'''

a = 1
b = 2
c = 0

print('======方法1======')
a = c
c = b
b = a

print('======方法2======')
a = a^b
b = a^b
a = a^b

print('======方法3======')
a,b = b,a